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Brain Tumors & Cancer

BRAIN TUMORS

Brain tumors affect approximately 190,000 people in the United States every year. They are the leading cause of childhood cancer deaths and the second leading death in individuals ages 20-39. Metastatic brain tumors occur in 10-15% of people with cancer and are the most common type of brain tumor. Primary brain tumors occur in approximately 14 per 100,000 people in the United States. The purpose of this section is to provide the reader with the basic information about brain tumors, the impact that they can have on functioning in children and adults, the impact of various forms of treatment (e.g., radiation or chemotherapy) and the role of the neuropsychologist in the pre- and post-treatment phases.

Primary brain tumors originate in the brain itself and do not typically spread outside the central nervous system. Primary brain tumors can be separated into two types: gliomas and non-glial tumors. The brain itself consists of two types of cells. Neurons are the cells that receive and send messages within the brain and make up what is referred to as gray matter (composed of cell bodies) and white matter (composed of axons). Glial cells play a supportive role within the brain by nourishing, protecting and supporting neurons. The types of glial cells include: astrocytes, microglia, oligodendroglia, satellite cells and Schwann cells. Astrocytes are star-shaped cells that provide physical support to the neurons, provide them with nutrients, remove parts of dead neurons and help regulate the content of extracellular space. Microglia, like astrocytes, are also involved in removal of dead neurons. Oligodendroglia make up the myelin sheath, a fatty covering that surrounds the axons of most neurons in order to speed up the conduction rate between neurons. Satellite cells provide support for neurons in the peripheral nervous system including nerves in various parts of the body. Schwann cells form the myelin sheath around neurons in the peripheral nervous system.

GLIAL TUMORS

As the name would indicate, astrocytomas develop from astrocytes. Although these tumors can be located anywhere in the brain, their most common location is in the frontal lobe. This is the most common primary central nervous system tumor type. There are four variants of astrocytomas that are classified from low to high grade or from slow to fast growing: Grade I Pilocytic Astrocytoma Grade II Low-Grade Astrocytoma Grade III Anaplastic Astrocytoma Grade IV Glioblastoma Multiforme

Pilocytic and low-grade astrocytomas tend to be slow-growing and typically have relatively well-defined borders. They rarely spread to other parts of the central nervous system and occur more commonly in children. Anaplastic astrocytomas grow faster and more aggressively than grade I or II tumors. They are less uniform in appearance and tend to invade neighboring brain tissue. Unlike the low-grade tumors, anaplastic astrocytomas are more common in men and women in their 30s to 50s. Glioblastoma multiforme or GBM is the most invasive type of glial tumor, which means that it commonly spreads to other parts of the brain, grows rapidly, and may be composed of several different types of cells. It may evolve from other types of brain tumors and is most common among the men and women ranging in age from the 50s to 70s. This type of tumor accounts for 23% of all primary brain tumors. Children are most prone to grades I and II astrocytomas, which tend to be cystic and located in the regions of the cerebellum and brainstem. In adults the tumors typically occur in the cerebrum and often invade across the corpus callosum. The symptoms of astrocytomas depend on their size and location within the brain matter, but the most common symptoms include headaches, seizures, speech problems, thinking problems, behavioral and cognitive changes, weakness and/or paralysis, visual changes and nausea and vomiting.

Brainstem gliomas are located at the base of the brain and can range from low to high grade. They occur most frequently in children between the ages of three and 10 years, but are also found in adults. Due to their location in and around the brain stem, the most frequent symptoms of brainstem gliomas include headaches, nausea, issues with swallowing, speech deficits, problems with balance, weakness or numbness in the arms or legs, facial weakness and double vision.

Ependymal tumors or ependymomas begin in the cells that line the central canal of the spinal cord or the ventricles of the brain, where cerebrospinal fluid is produced. They can be classified as supratentorial, meaning that they occur in the cerebral hemispheres, or infratentorial, which means that they occur in the back of the brain. Ependymal tumors can be either slow or fast growing but are usually localized to one area of the brain. They are common in children and in men and women in their 40s and 50s. Their peak occurrence rate is at age 5 and again at age 34. A consequence of ependymal tumors, due to the fact that they occur in the ventricles, is hydrocephalus. Hydrocephalus results from the fact that such tumors block the ventricles and prevent the cerebrospinal fluid from circulating. This results in an increase in pressure on the brain and can result in brain damage beyond that which is due to the direct impact of the tumor. Typical symptoms of ependymal tumors include headache, nausea, speech and balance abnormalities, problems swallowing, weakness or numbness in the arms and legs, facial weakness and double vision. A specific type of ependymal tumor is a subependymoma, which tends to be slow-growing and is usually located in the fourth and lateral ventricles. Typical symptoms include headache, nausea and loss of balance but there are instances when no symptoms occur and the tumor is found incidentally.

A mixed glioma is composed of two or more types of glial cells, most frequently a combination of an astrocytoma and an oligodendroglioma. These tumors are typically classified according to the most aggressive cell type that is present. They are common in men and women in their 20s through 50s and have symptoms that include headaches, seizures, weakness and paralysis, vision problems, behavioral and cognitive changes and nausea and vomiting.

Oligodendrogliomas are formed from oligodendrocytes and most frequently occur in the frontal or temporal lobes. Such tumors account for 4% of primary brain tumors, but between 12 and 20% of all infiltrating gliomas. They can be classified from low to high grade and while they can occur in children, are most commonly found in men and women in their 20s and 40s. This type of tumor may be associated with a genetic component, typically with deletions involving 1p or 19g. Symptoms include seizures, headaches, behavioral and cognitive changes and weakness or paralysis. Use this link for more information: http://www.medscape.com/viewarticle/515558_3.

NON-GLIAL TUMORS

Non-glial tumors develop from the cells of structures within the brain, including glands, blood vessels and nerves. The types of non-glial tumors are described below.

Acoustic Neuromas grow along the myelin sheath of the 8th cranial nerve (Vestibulocochlear Nerve) in the inner ear. The symptoms of these tumors include hearing loss in the affected ear, dizziness or vertigo due to the impact on the inner ear, tinnitus, tingling or numbness in the face and problems with balance and/or coordination. Such tumors are more common in women than in men.

CNS Lymphoma is a type of cancer that develops in the lymphatic system, which is responsible for supplying the white blood cells that fight infection and disease. These tumors tend to be aggressive and infiltrate multiple parts of the CNS. They are more common in individuals with compromised immune systems such as individuals infected with the HIV virus. CNS lymphomas are more common in men and more frequently found in older individuals typically in their 6th to 8th decade of life. Symptoms typically include headache, partial paralysis on one side of the body, seizures, cognitive and speech issues and vision deficits.

Medulloblastoma is a type of primitive neuroectodermal tumor (PNET) that is frequently found near the cerebellum or brainstem. It occurs most often in children under 10 years of age and is more common in males than females. Symptoms include headache, vomiting, decreased coordination, visual deficits, lethargy or sleepiness and behavioral and personality changes.

Meningiomas arise from the meninges (tissue layers) that surround the brain. They can range from high to low grade with high grade tumors being more aggressive and likely to recur. They are classified as follows: Grade I: Benign Meningioma

Grade II: Atypical Meningioma

Grade III: Malignant Meningioma

The typical symptom profile of meningioms includes headaches, problems with speech, memory and concentration, personality changes, vision problems (blurred or double vision, loss of peripheral vision), gradual loss of sensation or movement in an arm or leg , loss of balance or hearing, difficulty swallowing, drowsiness, seizures and decreased sense of smell.

THE ROLE OF THE NEUROPSYCHOLOGICAL EVALUATION There are a number of reasons why the neuropsychologist is an important member of the treatment team for individuals diagnosed with brain tumors. Any individual who has been diagnosed with a brain tumor should be referred for a neuropsychological evaluation. Optimally, the initial assessment should be conducted shortly after the tumor is diagnosed and prior to the commencement of treatment, including neurosurgery, if this is medically feasible. The initial assessment provides the treatment team with an understanding of how the tumor is affecting brain functioning and also provides a baseline against which future changes in cognitive, behavioral and emotional functioning can be compared. Once treatment has begun it is important to have follow-up neuropsychological evaluations as the treatment for brain cancer is often invasive (e.g., surgical resection of the tumor) and can cause injury to the brain. For example, radiation is not only harmful to the brain tumor but also to healthy brain tissue. Follow-up assessments can provide information not only about improvement after removal of the tumor, but also assess the impact of radiation and chemotherapy on functioning over time. Furthermore, many individuals need to undergo a period of rehabilitation to help restore cognitive and motor functioning. The neuropsychological evaluation is also used to assess quality of life and determine where rehabilitation will be most effective so that the treatment needs of the individual are refined, making the process more efficient.